1. Field of the Invention
The present invention relates to an image forming system provided with an image forming apparatus and an information processing apparatus that is connected to the image forming apparatus via a wireless communication means and transmits printing data to the image forming apparatus by wireless communication executed by the wireless communication means.
Further, the present invention relates to the image forming apparatus and the information processing apparatus that constitute the image forming system, a control method for the image forming apparatus, a control method for the information processing apparatus, and a storage medium storing a control program therefor.
2. Description of the Related Art
In recent years, a printer that executes wireless communication, such as wireless USB communication, with a host computer, and that can receive printing data from the host computer has spread. Such a printer has an advantage that an installation position can be freely changed as compared with a printer connected with a host computer via a cable.
However, when the host computer transmits printing data to the printer using the wireless communication, there is a problem that an error due to insufficient communication speed for normal data communication depending on surrounding environment can occur.
For example, an obstacle located between the host computer and the printer may decrease the communication speed due to reflection of a radio wave. Further, when a wireless communication terminal using the same frequency band is used near the host computer or the printer, the communication speed may fall.
When the communication speed between the host computer and the printer decreases due to these causes, a transmission process of the printing data cannot catch up the printing process of the printer side. This causes buffer under-run, and an error occurs in the printer.
At this time, a user cannot recognize easily that the obstacle or the use of the other wireless communication terminal has affected the communication speed between the host computer and the printer. That is, even when the error has occurred in the printer owing to the obstacle or the use of the other wireless communication terminal, a user cannot recognize easily what is the cause of the error, and the user may misunderstand the error as a failure of the printer.
Further, the decrease of the communication speed owing to the above described environment occurs at the timing including but not limited to the timing of installing the host computer or the printer. That is, also after a user starts use, an obstacle may be newly installed or a use of another wireless communication terminal that was not used may be started. In such a case, it becomes more difficult for a user to recognize that the decrease of the communication speed owing to the peripheral environment causes an error of the printer, as compared with the timing of installing the host computer or the printer.
In order to resolve these inconveniences, Japanese laid-open patent publication (Kokai) No. 2003-345537 (JP2003-345537A) discloses a technique to determine a quality of communication environment based on an actual communication speed and a parameter that has been set by a user to determine the quality of communication environment.
However, the technique disclosed in the above-mentioned patent publication requires a user to set the parameter for a communication environment examination beforehand. That is, the user must consider and set a reference value to determine whether the communication environment is good or needs to be improved. This requires sophisticated knowledge and troublesome operations of a user.
Especially, when the host computer transmits printing data to the printer using wireless communication, it is difficult for a user to set an appropriate reference value for the determination. That's because, the communication speed needed for receiving printing data normally varies depending on printing ability of a printer.
For example, a printer that can execute a printing process at high speed causes the above-mentioned buffer under-run if printing data is not transmitted at correspondingly high speed. On the other hand, a printer that can execute a printing process only at low speed does not cause the buffer under-run even if printing data is transmitted at relatively low speed.
Thus, since the lower limit of the communication speed at which an error does not occur varies depending on a printing ability of a printer, extremely sophisticated knowledge is needed to a user in order to set an appropriate reference value corresponding to each printer.